專案地址:https://github.com/heng1234/springdata-jpa

問題描述：

剛開始實體類程式碼是這樣寫的

package com.hvly.springjp_1.com.hlvy.entity;

import lombok.Data;

import javax.persistence.*;


/**
 * Customer
 *
 * @author heng
 **/

/**
 * 1、在@Entity下增加@NamedQuery定義 需要注意 query裡面的值也是JPQL 查詢引數也要和實體類對應起來
 * 因為實際場景中這種破壞ENtity的侵入式很不美 也不方便 所以這種方式容易一萬 工作中也很少推薦
 * 2、與之相對應的還有@NamedNativeQuery 用法一樣 唯一不同的是 query裡面放置的是原生SQL語句 而非實體類的欄位名字
 * name query的名稱 規則：實體類.方法名`
 */

@NamedQuery(name = "Customer.findByFirstName",
        query = "select c from Customer c where c.firstaname = ?1")
//@Data
@Entity
public class Customer {

    @Id
    @GeneratedValue(strategy = GenerationType.IDENTITY)//自動增遞
    private Long id;

    private String firstname;

    private String lastname;

    public Long getId() {
        return id;
    }

    public void setId(Long id) {
        this.id = id;
    }

    public String getFirstname() {
        return firstname;
    }

    public void setFirstname(String firstname) {
        this.firstname = firstname;
    }

    public String getLastname() {
        return lastname;
    }

    public void setLastname(String lastname) {
        this.lastname = lastname;
    }
}
 

CustomerJpaRepository

package com.hvly.springjp_1.com.hlvy.repository;

import com.hvly.springjp_1.com.hlvy.entity.Customer;
import org.springframework.data.jpa.repository.JpaRepository;

/**
 * Customer
 *
 * @author heng
 **/
public interface CustomerJpaRepository extends JpaRepository<Customer,Long>{

    /**
     * @NamedQuery查詢
     * @param firstName
     * @return
     */
    Customer findByFirstName(String firstName);
}
 

Controller

package com.hvly.springjp_1.com.hlvy.controller;

import com.hvly.springjp_1.com.hlvy.entity.Customer;
import com.hvly.springjp_1.com.hlvy.repository.CustomerJpaRepository;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.web.bind.annotation.RequestMapping;
import org.springframework.web.bind.annotation.RestController;

/**
 * CustomerController
 *
 * @author heng
 **/
@RestController
@RequestMapping("customer")
public class CustomerController {

    @Autowired
    private CustomerJpaRepository customerJpaRepository;

    /**
     * @NamedQuery查詢
     * @param firstName
     * @return
     */
    @RequestMapping("findByFirstName")
    Customer findByFirstName(String firstName){
        return customerJpaRepository.findByFirstName(firstName);
    }
}
 

結果啟動報錯： sql打印出來  from後面跟的是實體類路徑

接著我去網上看到這個https://blog.csdn.net/uhb6577/article/details/78998883

發現我已經加了@Entity註解

最後發現@NamedQuery(name = "Customer.findByFirstName",
        query = "select c from Customer c where c.firstaname = ?1")

多寫了個字母a 應該是  where c.firstname = ?1 而不是 where c.firstaname = ?1